Joint assemblies and method of inspecting thereof

ABSTRACT

A joint assembly is provided. The joint assembly includes a first component including a first bond surface and a second component including a second bond surface coupled to the first bond surface such that a bond line is defined therebetween. At least one of the first and second components includes a plurality of contrast particles that diffuse across the bond line when a predetermined amount of heat and pressure are applied to the first and second components.

BACKGROUND

The field of the present disclosure relates generally to compositejoints and, more specifically, to non-destructive bond strengthverification techniques for composite joints.

At least some known aircraft components may be fabricated frommulti-layer laminate structures of non-metallic composite materials suchas carbon-fiber-reinforced polymer (CFRP). Composite materials generallyhave a high strength-to-weight ratio and may be formed in a variety ofshapes and sizes. To reduce the weight of an aircraft, the compositematerials may be used in combination with metallic materials, such asaluminum, titanium, and/or steel. Reducing overall weight generallycontributes to increasing the fuel efficiency of the aircraft.

At least some known aircraft components fabricated from compositematerials may be bonded together with an adhesive material. While theadhesive material is generally effective at bonding the componentstogether, disbonding may occur during the service life of the aircraft.For example, disbonding may occur after prolonged use of the aircraftand/or may be caused when a foreign object impacts the materials duringflight. Such disbonding may be difficult to detect during scheduledmaintenance, and may be difficult to detect via visual inspection.

Moreover, it may be difficult and costly to verify that a successfulbond between the components has been formed during manufacture of apart. For example, at least one known method of verifying bond strengthincludes forming process verification coupons using the same processunder the same conditions as the part being formed. The strength of theprocess verification coupons is then evaluated via destructive testing,and the part is certified for service if the bond strength of thecoupons is greater than a predetermined threshold. However, forming andevaluating process verification coupons is a time-consuming andlaborious task, which provides only indirect bond strength verificationof the bond formed between the components.

BRIEF DESCRIPTION

In one aspect, a joint assembly is provided. The joint assembly includesa first component including a first bond surface and a second componentincluding a second bond surface coupled to the first bond surface suchthat a bond line is defined therebetween. At least one of the first andsecond components includes a plurality of contrast particles thatdiffuse across the bond line when a predetermined amount of heat andpressure are applied to the first and second components.

In another aspect, a joint assembly is provided. The joint assemblyincludes a first component including a first bond surface and a secondcomponent including a second bond surface configured to couple to saidfirst bond surface. The joint assembly also includes a layer of adhesivepositioned between the first and second bond surfaces such that a firstbond line is defined between the layer and the first bond surface, andsuch that a second bond line is defined between the layer and the secondbond surface. The layer of adhesive includes a plurality of contrastparticles that diffuse across at least one of the first and second bondlines when a predetermined amount of heat and pressure are applied tothe first and second components.

In yet another aspect, a method of inspecting a joint assembly isprovided. The method includes evaluating the joint assembly via anon-destructive inspection technique, obtaining an image of the jointassembly, and verifying bond formation between components in the jointassembly based on a location of contrast particles in the image. Thecontrast particles diffuse from a first location into at least one ofthe components when a predetermined amount of heat and pressure areapplied to the components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of an exemplary aircraft production and servicemethod.

FIG. 2 is a block diagram of an exemplary aircraft.

FIG. 3 is a schematic flow diagram illustrating a series of processsteps of forming an exemplary joint assembly.

FIG. 4 is a schematic flow diagram illustrating a series of processsteps of forming an alternative joint assembly.

FIG. 5 is a flow diagram of an exemplary method of inspecting a jointassembly.

DETAILED DESCRIPTION

The implementations described herein relate to joint assemblies andmethods of inspecting thereof. More specifically, the methods describedherein enable direct verification of bond formation between componentsin the joint assemblies, wherein the bond is formed in thermoplasticmaterials via diffusion at a bond interface. The direct verification isprovided by evaluating the joint assemblies via non-destructiveinspection (NDI) techniques, and the joint assemblies include contrastparticles dispersed therein that are capable of detection when evaluatedby the NDI techniques. For example, the contrast particles are initiallyeither located in the components themselves or in a layer of adhesivepositioned between the components. When a predetermined amount of heatand pressure are applied, such as an amount of heat and pressuretraditionally used to form the joint assemblies, the contrast particlesdiffuse across a bond line defined between the components. A location ofthe contrast particles in the finished joint assembly is determined bythe NDI evaluation, and successful bond verification is confirmed whenthe contrast particles are located within adjacent components of theassembly (i.e., when diffusion occurs).

Referring to the drawings, implementations of the disclosure may bedescribed in the context of an aircraft manufacturing and service method100 (shown in FIG. 1) and via an aircraft 102 (shown in FIG. 2). Duringpre-production, including specification and design 104 data of aircraft102 may be used during the manufacturing process and other materialsassociated with the airframe may be procured 106. During production,component and subassembly manufacturing 108 and system integration 110of aircraft 102 occurs, prior to aircraft 102 entering its certificationand delivery process 112. Upon successful satisfaction and completion ofairframe certification, aircraft 102 may be placed in service 114. Whilein service by a customer, aircraft 102 is scheduled for periodic,routine, and scheduled maintenance and service 116, including anymodification, reconfiguration, and/or refurbishment, for example. Inalternative implementations, manufacturing and service method 100 may beimplemented via platforms other than an aircraft.

Each portion and process associated with aircraft manufacturing and/orservice 100 may be performed or completed by a system integrator, athird party, and/or an operator (e.g., a customer). For the purposes ofthis description, a system integrator may include without limitation anynumber of aircraft manufacturers and major-system subcontractors; athird party may include without limitation any number of venders,subcontractors, and suppliers; and an operator may be an airline,leasing company, military entity, service organization, and so on.

As shown in FIG. 2, aircraft 102 produced via method 100 may include anairframe 118 having a plurality of systems 120 and an interior 122.Examples of high-level systems 120 include one or more of a propulsionsystem 124, an electrical system 126, a hydraulic system 128, and/or anenvironmental system 130. Any number of other systems may be included.

Apparatus and methods embodied herein may be employed during any one ormore of the stages of method 100. For example, components orsubassemblies corresponding to component and subassembly productionprocess 108 may be fabricated or manufactured in a manner similar tocomponents or subassemblies produced while aircraft 102 is in service114. Also, one or more apparatus implementations, methodimplementations, or a combination thereof may be utilized during theproduction stages 108 and 110, for example, by substantially expeditingassembly of, and/or reducing the cost of assembly of aircraft 102.Similarly, one or more of apparatus implementations, methodimplementations, or a combination thereof may be utilized while aircraft102 is being serviced or maintained, for example, during scheduledmaintenance and service 116.

As used herein, the term “aircraft” may include, but is not limited toonly including, airplanes, unmanned aerial vehicles (UAVs), gliders,helicopters, and/or any other object that travels through airspace.Further, in an alternative implementation, the aircraft manufacturingand service method described herein may be used in any manufacturingand/or service operation.

FIG. 3 is a schematic flow diagram illustrating a series of processsteps of forming an exemplary joint assembly 200. In the exemplaryimplementation, joint assembly 200 includes a first component 202 and asecond component 204. First component 202 includes a first bond surface206 and second component 204 includes a second bond surface 208 coupledto first bond surface 206 such that a bond line 210 is definedtherebetween. Moreover, at least one of first and second components 202and 204 include a plurality of contrast particles dispersed therein.Specifically, in one implementation, first component 202 includes aplurality of first contrast particles 212 dispersed therein, and secondcomponent 204 includes a plurality of second contrast particles 214dispersed therein. As will be described in more detail below, contrastparticles 212 and 214 diffuse across bond line 210 when a predeterminedamount of heat and pressure 216 are applied to first and secondcomponents 202 and 204.

First and second components 202 and 204 may be fabricated from anymaterial that enables joint assembly 200 to function as describedherein. An exemplary material used to fabricate components 202 and 204includes thermoplastic material such as, but not limited to, carbonfiber reinforced polymer. As such, fabricating components 202 and 204from thermoplastic material enables contrast particles 212 and 214 to bedispersed therein during formation thereof.

First and second contrast particles 212 and 214 may be fabricated fromany material that enables joint assembly 200 to function as describedherein. Specifically, in one implementation, first contrast particles212 are fabricated from a first material and second contrast particles214 are fabricated from a second material different than the firstmaterial in at least one feature such as material or size, for example.The materials used to fabricate first and second contrast particles 212and 214 are selected based on whether the materials are capable ofdetection when joint assembly 200 is evaluated by non-destructiveinspection techniques. For example, if the non-destructive inspectiontechnique implemented is eddy current testing, contrast particles 212and 214 are fabricated from an electrically conductive material such asgraphene.

Moreover, as described above, the first and second materials differ inat least one feature such that differentiation between first and secondcontrast particles 212 and 214 can be determined when evaluated bynon-destructive inspection techniques. As such, as will be described inmore detail below, bond formation between first and second components202 and 204 can be verified based on a location of contrast particles212 and 214 in joint assembly 200. In an alternative implementation,only one of first and second components 202 and 204 includes contrastparticles such that bond formation is detected when the contrastparticles diffuse across bond line 210.

First and second contrast particles 212 and 214 may also be of any sizethat enables joint assembly 200 to function as described herein. Forexample, in the exemplary implementation, contrast particles 212 and 214have a size of less than about 100 nanometers such that contrastparticles 212 and 214 readily diffuse across bond line 210 when heat andpressure 216 are applied. Moreover, utilizing particles of this sizefacilitates reducing modifications to the mechanical properties of thematerial used to fabricate first and second components 202 and 204.

In the series of process steps, first and second bond surfaces 206 and208 are coupled together and heat and pressure 216 are applied to firstand second components 202 and 204 forming a substantially unitarystructure. Heat and pressure 216 facilitates softening the thermoplasticmaterial of components 202 and 204 such that at least some of contrastparticles 212 and 214 diffuse across bond line 210. As such, bondformation between components 202 and 204 can be verified based on alocation of contrast particles 212 and 214 in joint assembly 200. Morespecifically, bond formation is verified based on a concentration ofcontrast particles 212 and 214 within a predetermined volume at alocation within joint assembly 200, or a distance that either contrastparticles 212 and 214 diffuse into opposing components 202 and 204,respectively.

FIG. 4 is a schematic flow diagram illustrating a series of processsteps of forming an alternative joint assembly 218. In the exemplaryimplementation, joint assembly 218 includes first component 202 andsecond component 204, and bond surfaces 206 and 208 are coupledindirectly together. A layer 220 of adhesive is positioned between bondsurfaces 206 and 208 such that a first bond line 222 is defined betweenlayer 220 and first bond surface 206, and a second bond line 224 isdefined between layer 220 and second bond surface 208. Moreover, unlikejoint assembly 200 (shown in FIG. 3), first and second components 202and 204 do not include contrast particles 212 and 214 dispersed therein.Rather, as will be described in more detail below, layer 220 of adhesiveincludes a plurality of contrast particles 226 that diffuse across atleast one first and second bond lines 222 and 224 when a predeterminedamount of heat and pressure 216 are applied to first and secondcomponents 202 and 204.

Layer 220 of adhesive includes a resin matrix 228 and contrast particles226 dispersed therein. Resin matrix 228 may be any material that enablesjoint assembly 218 to function as described herein. In the exemplaryimplementation, resin matrix 228 is fabricated from a third materialthat differs from the first material used to fabricate contrastparticles 226 such that differentiation therebetween can be determinedwhen evaluated by non-destructive inspection techniques.

In the series of process steps, layer 220 of adhesive is positionedbetween first and second components 202 and 204 and heat and pressure216 are applied thereto. Heat and pressure 216 facilitates softening thethermoplastic material of components 202 and 204, and facilitates curinglayer 220 of adhesive. As layer 220 cures, contrast particles 226dispersed therein diffuse across at least one of first and second bondlines 222 and 224. As such, bond formation between components 202 and204 can be verified based on a location of contrast particles 226 injoint assembly 218. More specifically, bond formation is verified basedon a distance that contrast particles 226 diffuse into each ofcomponents 202 and 204.

FIG. 5 is a flow diagram of an exemplary method 300 of inspecting ajoint assembly, such as joint assemblies 200 or 218 (shown in FIGS. 3and 4). In the exemplary implementation, method 300 includes evaluating302 the joint assembly via a non-destructive inspection technique, andobtaining 304 an image of the joint assembly. Exemplary non-destructiveinspection techniques include, but are not limited to, eddy currenttesting, tomography, terahertz imaging techniques, or x-ray imagingtechniques. In one implementation, the joint assembly is evaluated 302along a bond line, such as bond lines 210, 222, or 224, defined betweencomponents of the joint assembly.

Method 300 also includes verifying 306 bond formation between componentsin the joint assembly based on a location of contrast particles in theimage. The contrast particles diffuse from a first location into atleast one of the components when a predetermined amount of heat andpressure are applied to the components. For example, the first locationis within one of components 202 and 204 when evaluating joint assembly200, and the first location is within layer 220 of adhesive whenevaluating joint assembly 218. In one implementation, a resolution ofthe image is verified to be greater than a predetermined image qualitythreshold prior to verifying bond formation between components in thejoint assembly. If the resolution is less than the predetermined imagequality threshold, subsequent images are obtained until a suitable imagehas been obtained.

As described above, verifying 306 bond formation includes determining atleast one of a concentration of the contrast particles at the locationof the joint assembly or a distance that the contrast particles diffuseinto the at least one of the components. Moreover, verifying 306 bondformation includes determining differentiation between a first materialused to fabricate the plurality of contrast particles and a secondmaterial used to fabricate the components, or between first and secondmaterials if both are used to fabricate the components.

This written description uses examples to disclose variousimplementations, including the best mode, and also to enable any personskilled in the art to practice the various implementations, includingmaking and using any devices or systems and performing any incorporatedmethods. The patentable scope of the disclosure is defined by theclaims, and may include other examples that occur to those skilled inthe art. Such other examples are intended to be within the scope of theclaims if they have structural elements that do not differ from theliteral language of the claims, or if they include equivalent structuralelements with insubstantial differences from the literal language of theclaims.

What is claimed is:
 1. A joint assembly comprising: a first componentcomprising a first bond surface; and a second component comprising asecond bond surface coupled to said first bond surface such that a bondline is defined therebetween, wherein at least one of said first andsecond components comprises a plurality of contrast particles thatdiffuse across said bond line when a predetermined amount of heat andpressure are applied to said first and second components.
 2. Theassembly in accordance with claim 1, wherein said first componentcomprises a plurality of first contrast particles fabricated from afirst material and said second component comprises a plurality of secondcontrast particles fabricated from a second material different than thefirst material.
 3. The assembly in accordance with claim 2, wherein saidpluralities of first and second contrast particles are interspersed witheach other when the predetermined amount of heat and pressure areapplied.
 4. The assembly in accordance with claim 1, wherein saidplurality of contrast particles are fabricated from a first materialcapable of detection when evaluated by non-destructive inspectiontechniques.
 5. The assembly in accordance with claim 4, wherein saidplurality of contrast particles are fabricated from the first materialdifferent than a second material used to fabricate said first and secondcomponents such that differentiation between the first and secondmaterials is determined when evaluated by the non-destructive inspectiontechniques.
 6. The assembly in accordance with claim 1, wherein saidfirst and second components are fabricated from a thermoplasticmaterial.
 7. The assembly in accordance with claim 1, wherein contrastparticles of said plurality of contrast particles have a size of lessthan about 100 nanometers.
 8. A joint assembly comprising: a firstcomponent comprising a first bond surface; a second component comprisinga second bond surface configured to couple to said first bond surface;and a layer of adhesive positioned between said first and second bondsurfaces such that a first bond line is defined between said layer andsaid first bond surface, and such that a second bond line is definedbetween said layer and said second bond surface, wherein said layer ofadhesive comprises a plurality of contrast particles that diffuse acrossat least one of said first and second bond lines when a predeterminedamount of heat and pressure are applied to said first and secondcomponents.
 9. The assembly in accordance with claim 8, wherein saidlayer of adhesive comprises a resin matrix and said plurality ofcontrast particles dispersed within said resin matrix.
 10. The assemblyin accordance with claim 8, wherein said plurality of contrast particlesare fabricated from a material capable of detection when evaluated bynon-destructive inspection techniques.
 11. The assembly in accordancewith claim 10, wherein said plurality of contrast particles arefabricated from the first material different than a second material usedto fabricate said first and second components such that differentiationbetween the first and second materials is detected when evaluated by thenon-destructive inspection techniques.
 12. The assembly in accordancewith claim 10, wherein said plurality of contrast particles arefabricated from the first material different than a third material usedto fabricate said resin matrix.
 13. The assembly in accordance withclaim 8, wherein said first and second components are fabricated from athermoplastic material.
 14. The assembly in accordance with claim 8,wherein contrast particles of said plurality of contrast particles havea size of less than about 100 nanometers.
 15. A method of inspecting ajoint assembly, said method comprising: evaluating the joint assemblyvia a non-destructive inspection technique; obtaining an image of thejoint assembly; and verifying bond formation between components in thejoint assembly based on a location of contrast particles in the image,wherein the contrast particles diffuse from a first location into atleast one of the components when a predetermined amount of heat andpressure are applied to the components.
 16. The method in accordancewith claim 15 further comprising verifying a resolution of the image isgreater than a predetermined image quality threshold.
 17. The method inaccordance with claim 15, wherein verifying bond formation comprisesdetermining at least one of a concentration of the contrast particles atthe location within the joint assembly or a distance that the contrastparticles diffuse into the at least one of the components.
 18. Themethod in accordance with claim 15, wherein verifying bond formationcomprises determining differentiation between a first material used tofabricate the plurality of contrast particles and a second material usedto fabricate the components.
 19. The method in accordance with claim 15,wherein evaluating the joint assembly comprises evaluating the jointassembly along a bond line defined between the components.
 20. Themethod in accordance with claim 19 further comprising certifying thejoint assembly for service when the contrast particles diffuse acrossthe bond line.